1. Field of the Invention
This invention relates to the preparation of a patient's skin to ensure good electrical contact with a medical electrode, and more particularly to a device for automatically abrading the skin until the impedance at the interface between the skin and the abrading means drops to a predetermined value.
2. Description of the Prior Art
Medical electrodes are commonly used to perform a large number of medical tests, such as electrocardiograms. These electrodes are generally of the disposable variety having an electrolyte-impregnated pad surrounded by a housing which is adhesively secured to the skin. In order for the electrode to properly sense subcutaneous electrical signals, the skin of the patient must be prepared by abrading the skin on which the electrode is to be placed. This abrasion removes foreign matter and a layer of dead skin to ensure better electrical contact between the electrolyte pad and the patient's skin.
Skin preparation for medical electrodes is presently accomplished by manually rubbing the patient's skin with a pad containing a cleansing agent. The primary disadvantages of this technique are the length of time required to prepare the patient for a medical test utilizing medical electrodes and the inability to precisely control the degree of skin preparation. In many medical tests, such as an electrocardiogram, a large number of electrodes--on the order of 3 to 14--must be secured to the patient's skin. Preparation of the patient's skin by manual means requires a great deal of time, thereby making such tests fairly costly. Manual preparation of the skin is continued until it appears to the person applying the electrodes that the skin has been abraded sufficiently. However, since this visual technique is rather imprecise, skin abrasion is either insufficient to allow the electrode to accurately receive voltage levels or excessive, causing patient discomfort.
A new type medical electrode is described in copending application, Ser. No. 003,109, filed Jan. 15, 1979, and entitled "MEDICAL ELECTRODE AND SYSTEM FOR MINIMIZING MOTION ARTIFACTS". This medical electrode includes an abrasive pad impregnated with an electrolyte solution which is rotatably mounted in a cylindrical housing. The housing is surrounded by an annular rim having an adhesive coating securing the electrodes to the skin. Skin preparation is easily and quickly accomplished by rotating the pad against the skin of the patient after the electrode has been secured to the skin. One problem associated with use of the above-described electrode is the difficulty in determining when the skin has been sufficiently prepared. The pad of the electrode may be rotated manually to abrade the skin or preferably be rotated by power means such as an electric motor. Individual patients require different amounts of preparation because of their differing skin characteristics; thus, a constant amount of skin preparation by the abrasive pad of the electrode may be excessive in some cases and insufficient in others.